Subaru Enthusiasts Car Club of the Sierras - View Single Post

Dean · 2008-07-29, 02:11 PM

I agree, those voltages sound low. You could have a shorted cell and/or a bad regulator. A 1/2 decent battery with a full charge should be able to hold over 12.5 volts with a >50 watt headlight across it for at least a minute. A good one for probably 30-60 minutes.

Even float charging on a good battery happens at about 12.5-13 volts and 14-15+ under heavy charging after starting or other heavy discharge.

The fact that the system will go above 13 volts means it is likely not the alternator IMHO.

2008-07-29, 02:11 PM	#5
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	I agree, those voltages sound low. You could have a shorted cell and/or a bad regulator. A 1/2 decent battery with a full charge should be able to hold over 12.5 volts with a >50 watt headlight across it for at least a minute. A good one for probably 30-60 minutes. Even float charging on a good battery happens at about 12.5-13 volts and 14-15+ under heavy charging after starting or other heavy discharge. The fact that the system will go above 13 volts means it is likely not the alternator IMHO. __________________ I am a Commodore PET --- Now get off my lawn you kids...